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Introduction to some technical parameters of Lenovo 802.11n wireless adapter

Users always know little about the technical parameters of Lenovo 802.11n wireless adapter and thus can't find a balance between performance and specification of their wireless card. This article is an introduction to its technical parameters.

Affected configurations

The above symptom may occur on the following systems:

All Idea laptops and desktops

Solution

Wireless card’s performance has something to do with multipath such as SISO or MISO, bandwidth such as 40MHz or 20MHz and other factors. However throughput is the “real” measure of performance and it is the transmission capability that is available to applications after the overhead required to address the needs of upper layer protocols has been addressed. By definition, throughput is a subset of a device’s physical layer data rate while data rate is an expression of a device’s raw transmission capability at the lowest, physical layer.

MIMO (multiple input multiple output) leverages multipath. A MIMO system has a number of transmitters (N) and receivers (M) and a MIMO device with multiple antennas is capable of sending multiple spatial streams – spatially distinct data streams within the same channel. Of course the numerical value of N and M has much to do with wireless card’s performance.

While 802.11 a/b/g networks operate in a 20 MHz channel, 802.11n defines the use of 20 and 40 MHz channels. 40 MHz channels allow doubling of the data rate to 150 Mbps.

MIMO and channelization both directly affect a device’s data rate. According to different types of MIMO and different spatial stream (up) x spatial stream (down), 11n can be divided into several types as below, each with its own designed highest rate (bit/sec) and estimated maximum throughput (Bytes / sec).

Table 1 below offers some information about different MIMO and channelization.

MAX data rate

Estimated MAX throughput(Byte=8bits)

40MHz Bandwidth

20MHz Bandwidth

40MHz Bandwidth

20MHz Bandwidth

SISO
1x1

135 or 150Mbps/
135 or 150Mbps

65 or 72.22Mbps/
65 or 72.22Mbps

9-10MBps/9-10MBps

4-5MBps/4-5MBps

MISO
1x2

135 or 150Mbps/
270 or 300Mbps

65 or 72.22Mbps/
130 or144.44Mbps

9-10MBps/18-20MBps

4-5MBps/9-10MBps

MIMO
2x2

270 or 300Mbps/
270 or 300Mbps

130 or144.44Mbps/
130 or144.44Mbps

18-20MBps/18-20MBps

9-10MBps/9-10MBps

MIMO
2x3

270 or 300Mbps/
405 or 450Mbps

130 or 144.44Mbps/
195 or 216.7Mbps

18-20MBps/29-30MBps

9-10MBps/14-15MBps

MIMO
3x3

405 or 450Mbps/
405 or 450Mbps

195 or 216.7Mbps/
195 or 216.7Mbps

29-30MBps/29-30MBps

14-15MBps/14-15MBps

Table 1

According to some parameters above, users could get a rough comprehension about the relationship between data rate and MIMO as well as bandwidth. Table 2 below offers these technical parameters of some types of Lenovo 802.11n wireless adapter. Users could find a balance between performance and specification of their wireless card combining two tables together